The present disclosure relates to a method for forming an electrode on a surface of an n-type nitride semiconductor, a nitride semiconductor device using the same, and a manufacturing method thereof.
Nitride semiconductor, such as gallium nitride (GaN), has been used in various electronic elements. In particular, nitride semiconductor has been widely used in a semiconductor light emitting diode (LED) field, and the use of nitride semiconductor light emitting elements are being extended in coverage from backlight units (BLUs) for various displays such as optical communication and mobile display, computer monitors, and the like, to various lighting systems.
It may be difficult for a nitride semiconductor to form an ohmic-contact with some generally used electrode materials due to a high work function. It may be more difficult for an n-type nitride semiconductor layer, such as an n-type GaN, to form ohmic-contact with an N face rather than with a Ga face (G-face). Thus, a scheme of performing a buffered oxide etch (BOE) treatment or a laser treatment on a surface of an n-type nitride semiconductor layer before depositing an n electrode, or using a metal such as TiN as an n electrode, has been proposed. However, a heat treatment process at high temperatures may be involved. Undergoing a heat treatment at high temperatures may form a leakage path or may weaken a bonded portion of eutectic metal due to agglomeration of metal such as aluminum (Al). A metal, such as chromium (Cr), may be used as a substitute to improve ohmic-characteristics, but the low reflectivity of some metals such as chromium (Cr) may be undesirable for applications in a field such as light emitting elements.